Present in a modern automobile are numerous components subject to wear that hence can present malfunctioning. In many cases, in the event of malfunctioning of a component, driving of the automobile proves impossible or at least markedly limited. It is consequently necessary to envisage a preventive maintenance in order to seek to limit as much as possible any sudden malfunctioning of a component during driving of the automobile. For this reason, automobiles manufacturers envisage replacement and/or overhauling of a certain number of components at pre-set intervals of mileage and/or of life. However, it is very difficult to foresee precisely the effective duration of a component in so far as, on account of the inevitable constructional tolerances and of the different service lives, two apparently identical components may have markedly different effective durations. This forces manufacturers to make a choice, namely, whether to privilege the reliability at the expense of economy of service and hence replace the components on the basis of the worst situation, or else to privilege the economy of service at the expense of reliability and hence replace the components on the basis of the best situation. Both of the choices present advantages and disadvantages, and it is very difficult to find an optimal balance. In any case, whatever the choice made, there will always be customers that are not satisfied (on account of the reduced reliability or on account of the high operating costs).
In order to seek a solution to the problem described above methods for diagnosing components of automobiles have been proposed, said diagnostic methods ought to be able to foresee when a component starts to function in an improper way (even though it still functions, i.e., long before it fails altogether) to signal in due time to the driver the need to carry out in a short time (but not a particularly short time) a maintenance intervention. In this way, it is possible to obtain at the same time high reliability and high economy of service.
However, the diagnostic methods proposed up to now present various drawbacks in so far as they are costly to implement (on account of the computing power required and/or the need to install additional sensors that are normally not present on board an automobile) and are not very effective (i.e., they are frequently not able to provide correct diagnoses).